Commit 71c0efb6 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Paolo Abeni
Browse files

ipv6: Factorise ip6_route_multipath_add(). 



We will get rid of RTNL from RTM_NEWROUTE and SIOCADDRT and rely
on RCU to guarantee dev and nexthop lifetime.

Then, the RCU section will start before ip6_route_info_create_nh()
in ip6_route_multipath_add(), but ip6_route_info_create() is called
in the same loop and will sleep.

Let's split the loop into ip6_route_mpath_info_create() and
ip6_route_mpath_info_create_nh().

Note that ip6_route_info_append() is now integrated into
ip6_route_mpath_info_create_nh() because we need to call different
free functions for nexthops that passed ip6_route_info_create_nh().

In case of failure, the remaining nexthops that ip6_route_info_create_nh()
has not been called for will be freed by ip6_route_mpath_info_cleanup().

OTOH, if a nexthop passes ip6_route_info_create_nh(), it will be linked
to a local temporary list, which will be spliced back to rt6_nh_list.
In case of failure, these nexthops will be released by fib6_info_release()
in ip6_route_multipath_add().

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250418000443.43734-12-kuniyu@amazon.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 5a1ccff5

net/ipv6/route.c

+130 −75
Original line number Diff line number Diff line
@@ -5316,29 +5316,131 @@ struct rt6_nh { 
	struct fib6_info *fib6_info;

	struct fib6_config r_cfg;

	struct list_head list;

	int weight;

};



static int ip6_route_info_append(struct list_head *rt6_nh_list,

				 struct fib6_info *rt,

				 struct fib6_config *r_cfg)

static void ip6_route_mpath_info_cleanup(struct list_head *rt6_nh_list)

{

	struct rt6_nh *nh;

	int err = -EEXIST;

	struct rt6_nh *nh, *nh_next;



	list_for_each_entry(nh, rt6_nh_list, list) {

		/* check if fib6_info already exists */

		if (rt6_duplicate_nexthop(nh->fib6_info, rt))

			return err;

	list_for_each_entry_safe(nh, nh_next, rt6_nh_list, list) {

		struct fib6_info *rt = nh->fib6_info;



		if (rt) {

			free_percpu(rt->fib6_nh->nh_common.nhc_pcpu_rth_output);

			free_percpu(rt->fib6_nh->rt6i_pcpu);

			ip_fib_metrics_put(rt->fib6_metrics);

			kfree(rt);

		}



		list_del(&nh->list);

		kfree(nh);

	}

}



static int ip6_route_mpath_info_create(struct list_head *rt6_nh_list,

				       struct fib6_config *cfg,

				       struct netlink_ext_ack *extack)

{

	struct rtnexthop *rtnh;

	int remaining;

	int err;



	remaining = cfg->fc_mp_len;

	rtnh = (struct rtnexthop *)cfg->fc_mp;



	/* Parse a Multipath Entry and build a list (rt6_nh_list) of

	 * fib6_info structs per nexthop

	 */

	while (rtnh_ok(rtnh, remaining)) {

		struct fib6_config r_cfg;

		struct fib6_info *rt;

		struct rt6_nh *nh;

		int attrlen;



		nh = kzalloc(sizeof(*nh), GFP_KERNEL);

	if (!nh)

		return -ENOMEM;

	nh->fib6_info = rt;

	memcpy(&nh->r_cfg, r_cfg, sizeof(*r_cfg));

		if (!nh) {

			err = -ENOMEM;

			goto err;

		}



		list_add_tail(&nh->list, rt6_nh_list);



		memcpy(&r_cfg, cfg, sizeof(*cfg));

		if (rtnh->rtnh_ifindex)

			r_cfg.fc_ifindex = rtnh->rtnh_ifindex;



		attrlen = rtnh_attrlen(rtnh);

		if (attrlen > 0) {

			struct nlattr *nla, *attrs = rtnh_attrs(rtnh);



			nla = nla_find(attrs, attrlen, RTA_GATEWAY);

			if (nla) {

				r_cfg.fc_gateway = nla_get_in6_addr(nla);

				r_cfg.fc_flags |= RTF_GATEWAY;

			}



			r_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);

			nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);

			if (nla)

				r_cfg.fc_encap_type = nla_get_u16(nla);

		}



		r_cfg.fc_flags |= (rtnh->rtnh_flags & RTNH_F_ONLINK);



		rt = ip6_route_info_create(&r_cfg, GFP_KERNEL, extack);

		if (IS_ERR(rt)) {

			err = PTR_ERR(rt);

			goto err;

		}



		nh->fib6_info = rt;

		nh->weight = rtnh->rtnh_hops + 1;

		memcpy(&nh->r_cfg, &r_cfg, sizeof(r_cfg));



		rtnh = rtnh_next(rtnh, &remaining);

	}



	return 0;

err:

	ip6_route_mpath_info_cleanup(rt6_nh_list);

	return err;

}



static int ip6_route_mpath_info_create_nh(struct list_head *rt6_nh_list,

					  struct netlink_ext_ack *extack)

{

	struct rt6_nh *nh, *nh_next, *nh_tmp;

	LIST_HEAD(tmp);

	int err;



	list_for_each_entry_safe(nh, nh_next, rt6_nh_list, list) {

		struct fib6_info *rt = nh->fib6_info;



		err = ip6_route_info_create_nh(rt, &nh->r_cfg, extack);

		if (err) {

			nh->fib6_info = NULL;

			goto err;

		}



		rt->fib6_nh->fib_nh_weight = nh->weight;



		list_move_tail(&nh->list, &tmp);



		list_for_each_entry(nh_tmp, rt6_nh_list, list) {

			/* check if fib6_info already exists */

			if (rt6_duplicate_nexthop(nh_tmp->fib6_info, rt)) {

				err = -EEXIST;

				goto err;

			}

		}

	}

out:

	list_splice(&tmp, rt6_nh_list);

	return err;

err:

	ip6_route_mpath_info_cleanup(rt6_nh_list);

	goto out;

}



static void ip6_route_mpath_notify(struct fib6_info *rt,
@@ -5397,75 +5499,28 @@ static int ip6_route_multipath_add(struct fib6_config *cfg, 
{

	struct fib6_info *rt_notif = NULL, *rt_last = NULL;

	struct nl_info *info = &cfg->fc_nlinfo;

	struct fib6_config r_cfg;

	struct rtnexthop *rtnh;

	struct fib6_info *rt;

	struct rt6_nh *err_nh;

	struct rt6_nh *nh, *nh_safe;

	LIST_HEAD(rt6_nh_list);

	struct rt6_nh *err_nh;

	__u16 nlflags;

	int remaining;

	int attrlen;

	int err = 1;

	int nhn = 0;

	int replace = (cfg->fc_nlinfo.nlh &&

	int replace;

	int err;



	replace = (cfg->fc_nlinfo.nlh &&

		   (cfg->fc_nlinfo.nlh->nlmsg_flags & NLM_F_REPLACE));

	LIST_HEAD(rt6_nh_list);



	nlflags = replace ? NLM_F_REPLACE : NLM_F_CREATE;

	if (info->nlh && info->nlh->nlmsg_flags & NLM_F_APPEND)

		nlflags |= NLM_F_APPEND;



	remaining = cfg->fc_mp_len;

	rtnh = (struct rtnexthop *)cfg->fc_mp;



	/* Parse a Multipath Entry and build a list (rt6_nh_list) of

	 * fib6_info structs per nexthop

	 */

	while (rtnh_ok(rtnh, remaining)) {

		memcpy(&r_cfg, cfg, sizeof(*cfg));

		if (rtnh->rtnh_ifindex)

			r_cfg.fc_ifindex = rtnh->rtnh_ifindex;



		attrlen = rtnh_attrlen(rtnh);

		if (attrlen > 0) {

			struct nlattr *nla, *attrs = rtnh_attrs(rtnh);



			nla = nla_find(attrs, attrlen, RTA_GATEWAY);

			if (nla) {

				r_cfg.fc_gateway = nla_get_in6_addr(nla);

				r_cfg.fc_flags |= RTF_GATEWAY;

			}



			r_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);

			nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);

			if (nla)

				r_cfg.fc_encap_type = nla_get_u16(nla);

		}



		r_cfg.fc_flags |= (rtnh->rtnh_flags & RTNH_F_ONLINK);

		rt = ip6_route_info_create(&r_cfg, GFP_KERNEL, extack);

		if (IS_ERR(rt)) {

			err = PTR_ERR(rt);

			rt = NULL;

			goto cleanup;

		}



		err = ip6_route_info_create_nh(rt, &r_cfg, extack);

		if (err) {

			rt = NULL;

			goto cleanup;

		}



		rt->fib6_nh->fib_nh_weight = rtnh->rtnh_hops + 1;

	err = ip6_route_mpath_info_create(&rt6_nh_list, cfg, extack);

	if (err)

		return err;



		err = ip6_route_info_append(&rt6_nh_list, rt, &r_cfg);

		if (err) {

			fib6_info_release(rt);

	err = ip6_route_mpath_info_create_nh(&rt6_nh_list, extack);

	if (err)

		goto cleanup;

		}



		rtnh = rtnh_next(rtnh, &remaining);

	}



	/* for add and replace send one notification with all nexthops.

	 * Skip the notification in fib6_add_rt2node and send one with